1. Field
The present invention relates generally to wireless messaging communication, and more specifically to techniques for converting short messages between different formats used by different wireless communication systems (e.g., GSM and CDMA).
2. Background
Short Message Service (SMS) is a service that supports the exchange of SMS or short messages between mobile stations and a wireless communication system. These short messages may be user-specific messages intended for specific recipient mobile stations or broadcast messages intended for multiple mobile stations.
SMS may be implemented by various types of wireless communication systems, two of which are code division multiple access (CDMA) systems and time division multiple access (TDMA) systems. A CDMA network may be designed to implement one or more standards such as cdma2000, W-CDMA, IS-95, and so on. A TDMA network may also be designed to implement one or more standards such as Global System for Mobile Communications (GSM). Each network typically further implement a particular mobile networking protocol that allows for roaming and advanced services, with ANSI-41 being commonly used for CDMA networks (except for W-CDMA) and GSM Mobile Application Part (GSM-MAP) being used for GSM and W-CDMA networks.
Since SMS is network technology dependent (ANSI-41 or MAP), CDMA and GSM networks that implement different network technologies support different implementations of SMS. Each SMS implementation has different capabilities and utilizes different message types and formats for sending short messages. Each SMS implementation may allow for different processing on short messages. For example, for the SMS implementation in GSM-MAP, the user data in a short message may be sent in a compressed or uncompressed form, with the compression algorithm being defined by a standard. For simplicity, the SMS implementation in GSM-MAP based networks is referred to as GSM SMS, and the SMS implementation in ANSI-41 based networks is referred to as CDMA SMS.
Although CDMA and GSM are quite different in design, an interworking and interoperability function (IIF) has been defined to allow for communication between these two different types of networks. The result is that improved coverage and performance may be attained for mobile users or subscribers of the networks. In particular, through the IIF, a GSM mobile user may roam into the coverage area of a CDMA network and can continue to receive service, and vice versa.
If the CDMA and GSM networks both support SMS, then one of the functions of the IIF is to convert each short message originated from one network into the proper format required by the other network prior to forwarding the message to the other network. However, because CDMA and GSM networks with different network technologies support different implementations of SMS, it may not be possible under the current standards for CDMA SMS and GSM SMS to convert a short message for one system into the specific format required by the other system. For example, since GSM SMS supports both compressed and uncompressed user data and CDMA SMS does not support the compressed format, the IIF would need to decompress the user data in a compressed GSM SMS message and then converts it to a CDMA SMS message. Moreover, the GSM SMS message may contain other fields that do not exist in the CDMA SMS message.
There is therefore a need in the art for techniques to convert GSM SMS messages to CDMA SMS messages, and vice versa, such that the problems described above are ameliorated.